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I survived the first week in Chem !!!!

I survived the first week in Chem !!!!. Prefix mini- quiz. There are many competing choices of prefixes for a given quantity in chemistry (and physics and biology) Nobody follows the rules……. “ How do I convert between these %%&! prefix systems ?”. EXAMPLE.

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I survived the first week in Chem !!!!

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  1. I survived the first week in Chem !!!!

  2. Prefix mini- quiz

  3. There are many competing choices of prefixes for a given quantity in chemistry (and physics and biology) Nobody follows the rules…… “How do I convert between these %%&! prefix systems ?” EXAMPLE Common prefix units used to define wavelength, : • m • nm • pm • mm (millimicron) • Å =10-1 nm

  4. 15 m = ??? pm

  5. How to convert ??? Method 1) Algebraic (‘Marine’ way) Doc’s story about his HS chem teacher Divide and conquer, maggot !

  6. The `Marine’ way of conversion: 15 m = ___?____ pm Divide: 15 m = ___?____pm pm pm Conquer (substitute and calculate) 15 10-6 = ___?____ 10-12 =15*10-6-(-12) =15*10+6

  7. Method 2) Factor-label (commonly taught by high school teachers)

  8. `factor-label’ way of conversion: 15 m = ___?____ pm 1) Convert to base units (m) 15 m * 10-6 m m 2) Convert to base units to desired units & compute 15 m * 10-6 m m 1012 pm m =15*1012-6 pm =15*10+6 pm

  9. metric-Metric conversion problems done both ways (on board) • How many cm in 5 dm • How many pg in 50 ng ? 5*101 =50 cm 50*103 pg=5*104 pg =50,000 pg

  10. More Guided practice Unit conversions(via factor-label & Algebraic) answers 4.57*104 g Convert 45.7 kg to g Convert 0.73 mL to L 730 L =7.3*102 L Convert 7.2 kg/L to mg/ L 7.2 mg/L

  11. U-DO-IT !!! How many dg in 2.4 kg ? 2.4*104 dg 23 nm = ? m 2.3*10-2m Convert 5.0*103 ps to its equivalent in ms 5*10-6 ms 6 pg/L = ?? g/mL 6*10-3 g/mL

  12. 5 ng= _____pg ? • 500 pg • 5000 pg • 50 pg • 0.5 pg

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